Dendrobium suzukii T.Yukawa

Averyanov, Leonid V., Ponert, Jan, Nguyen, Phi Tam, Duy, Nong Van, Khang, Nguyen Sinh & Nguyen, Van Canh, 2016, A survey of Dendrobium Sw. sect. Formosae (Benth. & Hook. f.) Hook. f. in Cambodia, Laos and Vietnam, Adansonia 38 (2), pp. 199-217 : 205-206

4. Dendrobium suzukii T.Yukawa

Acta Phytotaxonomica et Geobotanica 53: 12, figs 1, 2 (2002).

Dendrobium cruentum auct. non Rchb.f.: Aver. & Averyanova, Updated Checklist of the Orchids of Vietnam: 27 (2003).

TYPUS. — S Vietnam. Ninh Thuan Province, in the vicinity of Nonh Son, Flowering in cultivation August 2001, Hort . T. Sato s.n. (holo-, TNS).

HABITAT, PHENOLOGY AND CONSERVATION STATUS. — Epiphyte on tall trees in primary closed evergreen broad-leaved and mixed seasonal mountain forest on rocky shale, granite and limestone. 1000-1150 m. Fl. April-June. Very rare. Expected IUCN Red List status – CR.

DISTRIBUTION. — Vietnam (Lai Chau, Lam Dong). Endemic .

MATERIAL EXAMINED. — Vietnam. Lai Chau, sine loc., L . Averyanov HAL 2905, 2. V .2003 ( LE photo); Lam Dong, Dalat area , sine loc., L. Averyanov s.n., 16. V .2000 ( LE photo); Lam Dong, Dalat area , sine loc., L . Averyanov s.n., XI.2013 ( LE photo); Lam Dong, Duc Trong, Ta Nang , Duy s.n., III.2014, Duy s.n., VI .2014 ( LE photo); Lam Dong, sine loc., S . Kruekerd KV-0011 ( TNS) .

DESCRIPTION

Stems stout, narrowly fusiform, old distinctly flexuose, (20)25- 60(70) cm long, 0.8-1.5 cm in diameter, of many nodes. Leaves narrowly ovate to oblong, 4-8(10) cm long, 1-2.2 cm wide. Inflorescence 1-3(4), each with 1-2 flowers; floral bracts broadly lanceolate, acuminate, 1-1.5 cm long. Pedicel and ovary green, curved, 2-2.5 cm long. Flowers odorless, widely opening, 4-5 cm across, pale yellowish, lip side lobes and disc bright red, margin of epichile white, column and anther cap pale yellowish to greenish. Sepals and petals subsimilar in shape, triangular ovate, acute to acuminate, recurved, 2.4-3(3.5) cm long, 0.7-1.2(1.4) cm wide, petals distinctly smaller. Lip shortly clawed, obovate, 3-lobed, 2.5-3(3.4) cm long, 2.2-2.6 cm wide, with a semi globose callus at base; side lobes erect, falcate, obtuse, 10-12 mm long, 5-8 mm wide; median lobe obovate, obtuse, undulate, recurved, 1.5-2(2.2) cm long, 1-1.5(1.8) cm wide, with 5-7 prominent, cristateverrucose keels. Mentum broadly conic to almost hemispheric, 1.2-1.6 cm long and wide. Column dull yellowish, 5-6 mm tall and wide; anther cap cucullate, cubic, 3-4 mm tall and wide ( Fig. 1F, G ).

REMARKS

The species has a remarkable history. It was discovered by local commercial collectors around the years 1999-2000, when a lot of wild collected flowering plants entered street orchid markets in Dalat city and neighboring towns. Then for a long time, this species was only known on the basis of purchased specimens cultivated in orchid collections in Vietnam and abroad. It was tentatively recorded that the plants originated from at least two localities: in Lam Dong and in Lai Chau provinces. It is only in 2014 that the natural area with a few highly depleted populations was discovered by Vietnamese botanists – Dr. Nong Van Duy and Mr. Nguyen Phi Tam in remnant primary forest of Dalat city area near the junction of the borders of Binh Thuan, Lam Dong and Ninh Thuan provinces. The species was observed as a very rare epiphyte on old trees of Canarium sp. and Podocarpus neriifolius . The occurrence of D. suzukii in Lai Chau province still needs to be verified by field investigations. In any case a few doubts remains that this unique endemic stands in Vietnam on the verge of full extinction and urgently needs special studies and governmental protection.

According to the original description Dendrobium suzukii is most similar to D. cruentum but can be distinguished by the following characters: “1) much larger perianth lobes; 2) a semi-globose callus on the basal part of the labellum; 3) five, instead of three, keels on the labellum; 4) undulate margins on mid lobe of the labellum; 5) a wider callus with cristate, instead of verrucose, protuberances on the mid lobe of the labellum”.

Figures

FIG. 1. — A, B, Dendrobium bellatulum Rolfe; A, VH 2566; B, VH 2567; C, D, D. christyanum Rchb.f.; C, VH 950; D, CPC 6038; E, D. scabrilingue Lindl. (Konstantinov 29); F, G, D. suzukii T.Yukawa; F, Duy s.n., III.2014; G, L.Averyanov s.n., XI.2013); H, D. draconis Rchb.f. (HLF 7347); I, D. kontumense Gagnep.(LA-VN 21a). Photos: A-D, G-I, L. Averyanov; E, E. Konstantinov; F, N.V. Duy.